Coumarin-containing amphiphilic block copolymers with different compositions, as a new class of pH- and photo-responsive flocculants, were synthesized through reversible addition-fragmentation chain transfer polymerization of dimethyl aminoethyl methacrylate (DMAEMA), methyl methacrylate, and 7-acryloyloxy 4-methylcoumarin. Proton nuclear magnetic resonance spectroscopy was used to study the structure and composition of the copolymers. Zeta potential results show that the copolymers are applicable as amphoteric flocculants. The optimal flocculant concentration was calculated using the Jar analysis for kaolin flocculation, and the results show that the flocculation dependence on the flocculent concentration decreases with increasing its molecular weight. The dominance of charge neutralization in the flocculants with lower molecular weights and the dominance of adsorption bridging and hydrophobic association in the flocculants with higher molecular weights were indicated. These results are in agreement with the rheological data. To investigate the governing mechanism more precisely, the flocculation rate was calculated using turbidity measurements at different pH values over time. The highest final flocculation rate (99.25 %) corresponds to pH 4.5, which caused by the protonation of the amine groups of the DMAEMA repeating units. The dependence of settling rate on pH indicates the pH-dependent performance of the flocculants. Finally, fluorescence microscopy image of the flocculants shows its proper functioning of in the vicinity of kaolin, which has a promising industrial application.

中文翻译：

---

可逆加成断裂链转移聚合合成多刺激响应絮凝剂：研究高岭土混凝性能和机理


通过甲基丙烯酸二甲氨基乙酯（DMAEMA）、甲基丙烯酸甲酯和7-丙烯酰氧基4-的可逆加成-断裂链转移聚合反应合成了不同组成的含香豆素两亲性嵌段共聚物，作为一类新型pH响应和光响应絮凝剂。甲基香豆素。使用质子核磁共振波谱研究了共聚物的结构和组成。 Zeta电位结果表明该共聚物适合作为两性絮凝剂。利用高岭土絮凝的Jar分析计算了最佳絮凝剂浓度，结果表明，絮凝对絮凝剂浓度的依赖性随着其分子量的增加而减小。表明了较低分子量絮凝剂中电荷中和的主导作用以及较高分子量絮凝剂中吸附桥联和疏水缔合的主导作用。这些结果与流变数据一致。为了更精确地研究控制机制，使用不同 pH 值随时间变化的浊度测量值来计算絮凝率。最高的最终絮凝率 (99.25%) 对应于 pH 4.5，这是由 DMAEMA 重复单元的胺基的质子化引起的。沉降速率对 pH 值的依赖性表明了絮凝剂的 pH 依赖性性能。最后，絮凝剂的荧光显微镜图像显示了其在高岭土附近的正常功能，这具有广阔的工业应用前景。